The statement, from the office of President Joyce Banda, said Madonna has wanted special treatment and criticised her charity work, which focuses on schoolbuilding projects.

It said: "Kindness, as far as its ordinary meaning is concerned, is free and anonymous. If it can't be free and silent, it is not kindness, it is something else. Blackmail is the closest it becomes."

The singer said she would "continue to follow through on my commitment to help educate the children of Malawi".

She added: "I'm saddened that Malawi's president has chosen to release lies about what we've accomplished, my intentions, how I personally conducted myself while visiting Malawi and other untruths. I have no intentions of being distracted by these ridiculous allegations.

"I came to Malawi seven years ago with honourable intentions. I returned earlier this month to view the new schools we built. I did not ever ask or demand special treatment at the airport or elsewhere during my visit. I will not be distracted or discouraged by other people's political agendas. I made a promise to the children of Malawi and I am keeping that promise".

A spokeswoman for the singer suggested the criticism was inspired by the removal of the president's sister from her role heading Madonna's humanitarian organisation in the country.